摘要
[目的]研究菲(Phe)在不同根际距离中的降解和根际区域微生物群落结构变化,获得最佳降解效果的根际距离和降解微生物种类,为阐明红树林根际效应对海岸带多环芳烃(PAHs)降解的强化作用和机制提供参考.[方法]利用根际箱分离4个连续的隔间,其距离分别为0～2 mm、2～4 mm、4～6 mm隔间(根际)和>6 mm隔间(非根际),分别于0、10、20、30、40和50 d测定不同根际距离的Phe残留浓度、沉积物理化性质、微生物生物量和细菌群落结构,并采用冗余分析(RDA)探明Phe残留浓度与环境因子及细菌群落结构的相关性.[结果]靠近根际表面的沉积物(0～2 mm隔间)Phe降解效率最高(74.73%).在培养50 d后,对比不同间隔的理化性质变化,与第0 d相比,0～2 mm隔间变化最明显,pH降低3.84%,有机质含量提高16.14%;>6 mm隔间腐殖质含量升高12.56%.在Phe降解过程中,沉积物pH和腐殖质含量随着红树林根际距离的增加而增加,有机质含量随着根际距离的增加而减少.培养50 d后,微生物量碳(MBC)、微生物量氮(MBN)和微生物呼吸强度(SMR)总体上在0～2 mm隔间均为最高,分别为216.45、68.20和147.35 mg/kg,且均随着根际距离增加而降低.培养结束后,在0～2 mm、2～4 mm和4～6 mm隔间优势细菌属中,短杆菌属(Brevibacterium)和乳酸杆菌属(Lactobacillus)的相对丰度随根际距离的增加不断减少,脂环酸芽孢杆菌属(Ali-cyclobacillus)的相对丰度则随根际距离的增加不断增加.RDA结果表明,Phe残留浓度主要受降解功能微生物及环境因子影响,与脂环酸芽孢杆菌属、短杆菌属、乳酸杆菌属及有机质呈负相关.[结论]红树林根际效应可通过影响根际区沉积物的理化性质,从而改变细菌群落结构和微生物活性,以强化Phe降解,对消除海岸带生态系统中PAHs污染具有积极影响.
Abstract
[Objective]To study the degradation of phenanthrene(Phe)in different rhizosphere distances and the structural changes of microbial communities in the rhizosphere region,and to obtain the rhizosphere distances and degrad-ing microbial species with the best degradation effect,in order to provide reference for elucidating the enhancement of mangrove rhizosphere effects on the degradation of polycyclic aromatic hydrocarbons(PAHs)in the coastal zone and the mechanism.[Method]In this study,four consecutive compartments with rhizosphere distances of 0-2 mm,2-4 mm,4-6 mm(rhizosphere)and>6 mm(non-rhizosphere)were separated using rhizosphere boxes,and the Phenanthrene residue concentration,sediment physicochemical properties,microbial biomass,and bacterial community structure were deter-mined at different rhizosphere distances at 0,10,20,30,40,and 50 d.The results of the study were summarized in the fol-lowing table,which was supplemented by the results of the redundancy analysis.Redundancy analysis was used to investi-gate the correlation between Phenanthrene residue concentration and environmental factors and bacterial community struc-ture.[Result]The results of the study showed that the Phe degradation efficiency was highest in the sediments close to the rhizosphere surface(0-2 mm compartment,74.73%).After 50 d of incubation,comparing the physicochemical properties of different compartments,Comparison of 0 d and 50 d,the most significant changes were observed in the 0-2 mm com-partment,with a decrease of 3.84%in pH and a 16.14%increase in organic matter;humus was elevated by 12.56%in the>6 mm compartment.During the degradation process of Phe,the pH and humus content of the sediment increased with the increase of the rhizosphere distance of the mangrove forests,and the content of organic matter decreased with the increase of the rhizosphere distance..Microbial biomass carbon(MBC),microbial biomass nitrogen(MBN)and micro-bial respiratory strength(SMR)were,in general,the highest in the 0-2 mm compartment,at 216.45,68.20 and 147.35 mg/kg,respectively,and all of them decreased with increasing rhizosphere distance.At the end of incubation,Alicyclobacillus,Brevibacterium and Lactobacillus were the dominant functional genera in the rhizosphere microbial community in 0-2 mm,2-4 mm and 4-6 mm compartments.Brevibacterium and Lactobacillus continued to decrease with increasing rhizo-sphere distance,and Alicyclobacillus continued to increase in relative abundance with increasing rhizosphere distance.Re-dundancy analysis showed that Phe residue concentration was mainly affected by degradation function microorganisms and environmental factors,and was negatively correlated with Alicyclobacillus,Brevibacterium,and Lactobacillus,as well as organic matter.[Conclusion]Mangrove rhizosphere effects can enhance the degradation of Phe by affecting the physico-chemical properties of sediments in the rhizosphere zone,thereby changing the structure of bacterial communities and mi-crobial activity,and have a positive impact on the elimination of PAHs pollution in the coastal zone ecosystem.
基金项目
国家自然科学基金项目(41977125)
国家自然科学基金项目(41907033)
广东省自然科学基金项目(2022A1515010867)
广东省自然科学基金项目(2022A1515010630)
国家科技期刊平台
NSTL
万方数据